rtc: remove unneeded 'fast_io' parameter in regmap_config

When using MMIO with regmap, fast_io is implied. No need to set it
again.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250813161517.4746-18-wsa+renesas@sang-engineering.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: Wolfram Sang

drivers/rtc/rtc-meson.c

@@ -72,7 +72,6 @@ static const struct regmap_config meson_rtc_peripheral_regmap_config = {
 	.val_bits	= 32,
 	.reg_stride	= 4,
 	.max_register	= RTC_REG4,
-	.fast_io	= true,
 };
 
 /* RTC front-end serialiser controls */